CLEARANCE OF MUCUS FROM ENDOTRACHEAL-TUBES DURING INTRATRACHEAL PULMONARY VENTILATION

Background: Intratracheal pulmonary ventilation (ITPV) is a form of tr acheal gas insufflation in which all gas emerges in a cephalad directi on from the tip of a reverse-thrust catheter positioned within an endo tracheal tube. In vitro experiments have shown that this rapid gas flo w, with 5 ml/h of normal saline added to the gas flow, continuously re moves tracheal secretions from within the endotracheal tube. The autho rs evaluated its effectiveness to remove mucus in long-term studies in sheep. Methods: Fourteen healthy sheep were tracheally intubated and ventilated for 3 days with ITPV or with volume-controlled ventilation. Measurements were made of the total amount of secretions within the e ndotracheal tubes (weight gain), the protein content within the endotr acheal tubes, and the increase in resistance to constant air flow. The structure of the airways was examined grossly and histologically. Thr ee additional sheep were ventilated for 24 h with ITPV, and Evans Blue dye was added to the saline to assess the distribution of the infused saline. Results: There was significantly less mucus in endotracheal t ubes of sheep ventilated with ITPV than with conventional ventilation, as shown by minimal weight gain (0.70 +/- 0.14 g vs. 2.44 +/- 0.81 g; P < 0.001), lower protein content (14.09 +/- 10.79 mg us. 294.99 +/- 153.06 mg; P < 0.001), and lower resistance to constant air flow (6.15 +/- 0.54 cm H2O.l(-1).s(-1) vs. 15.34 +/- 5.28 cm H(2)0.l(-1).s(-1); P < 0.001). Results of gross and histological examinations of the trac heas of animals in both groups were similar, and the tracheas were wel l preserved. More than 95% of the instilled saline was recovered durin g ITPV. Only traces of Evans Blue dye were found near the tip of the e ndotracheal tubes. Conclusions: Intratracheal pulmonary ventilation ma kes it possible to keep the endotracheal tubes of sheep ventilated for 3 days free of mucus without suctioning.